Zinc–rich inorganic silicate anticorrosive coating incorporating muscovite for steel bars in sand–based autoclaved aerated concrete

Abstract

Corrosion is a thorny problem when steel reinforcement in sand–based autoclaved aerated concrete (SAAC) is in use. In this study, potassium silicate was used as the base material and muscovite and zinc powder were added as fillers to improve the coating properties. In addition to physical and mechanical properties, electrochemical tests including potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) were performed on the coatings. The phase composition, chemical composition and morphological differences of different coatings were also characterized. The results showed that zinc powder increased the density of the muscovite–potassium silicate coating and significantly improved the corrosion resistance and mechanical properties of the coatings. The prepared coatings exhibited stable qualities with no heat absorption and release before 365 °C. The adhesive strength and impact resistance of the coatings were as high as 2.43 MPa and 50 kg cm, respectively. The electrochemical test results showed that the coating resistance (Rc), charge-transfer resistance (Rct), and polarization resistance (Rp) of the C-5.5–55–40 coating were 23578, 3.542 × 105, and 2.911 × 105 Ω cm2, respectively, which exhibited the optimal corrosion resistance.